Mark Haub, a nutrition professor, decided to eat unhealthy foods. And he lost weight.
He may have been eating Twinkies and the like, but he ate only 1800 Calories a day. This demonstrates the most important aspect of weight loss, the need to consume fewer Calories than you burn.
This is another example why I question the motives of people who rail against certain foods, such as hydrogenated oils and corn syrup. In the end, everything you eat gets converted to energy.